President Trump has said the U.S. is now out of the Paris climate accord. In his speech in the Rose Garden yesterday, he listed off the reasons. Mainly, he said, the deal would hurt American workers. But the president also argued that the accord itself won't really make a difference on climate change. Here's President Trump.

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PRESIDENT DONALD TRUMP: Even if the Paris Agreement were implemented in full with total compliance from all nations, it is estimated it would only produce a two-tenths of one degree - think of that - this much - Celsius reduction in global temperature by the year 2100 - tiny, tiny amount.

MARTIN: OK. We're going to take a closer look at some of the president's assertions, including what he just said. And we're going to do so with the help of NPR science correspondent Chris Joyce. Hi there.

CHRISTOPHER JOYCE, BYLINE: How are you doing?

MARTIN: I am well. OK, we heard the president say tiny, tiny amount.

JOYCE: Right.

MARTIN: Is he right?

JOYCE: Well, that came from an MIT study that was done in 2014. The author of that study, as of today, has said that's a misrepresentation. The reason being that the initial study by MIT scientists came up with that number in 2014 well before they got the full deal on what the countries were going to do to reduce emissions.

MARTIN: So he's citing an incomplete, outdated study.

JOYCE: They redid the study in 2016 when they had the real numbers from the Paris Agreement. The numbers they came up with was a reduction of 0.6 to 1.1 degrees centigrade. So it's three to - at least three times more than the initial number. Furthermore, we're talking about a 2 degree difference here, which - it is the target of keeping temperatures going above two degrees Celsius.

MARTIN: Which can still make a difference.

JOYCE: Yeah, and so 1.1 is a big part of 2.

MARTIN: All right. Will the U.S. leaving this accord change the effectiveness of the overall deal?

JOYCE: It could if other countries drop out certainly. I mean, the U.S. emissions actually, within this country, are going down and have been going down for years. That could reverse after 2020. And particularly then, if the rest of the world drops out, that would have a serious effect on the climate.

MARTIN: And lastly, the president took particular umbrage at part of the deal called the Green Climate Fund. He said that it's simply a transfer of wealth from us to them, them being developing countries. Can you explain that briefly?

JOYCE: Yeah. That's a $100 billion fund by 2020 that would be money from the developed world going to the developing world. But that money, though, is supposed to be programmed for climate research and climate effort to deal with climate change, not to make cars to compete with the U.S. Furthermore, half of that money is supposed to come from the private sector, from banks, not from taxpayers.